Figure 29: Short Frame Pcm Timing; Figure 30: Long Frame Pcm Timing - Siemens AC75 Hardware Interface Description

AC75 Hardware Interface Description
Strictly confidential / Preliminary
The timing of a PCM short frame is shown in Figure 29. 16-bit data are transferred in both
directions at the same time during the first 16 clock cycles after the frame sync pulse. The
duration of a frame sync pulse is one BITCLK period, starting at the rising edge of BITCLK.
TXDAI data is shifted out at the next rising edge of BITCLK. Data transmitted from RXDAI of
the internal application is sampled at the falling edge of BITCLK.
BITCLK
FS
TXDAI
RXDAI
The timing of a PCM long frame is shown in Figure 30. 16-bit data are transferred in both
directions at the same time during the frame sync pulse FS is high. For this reason the
duration of a frame sync pulse is 16 BITCLK periods, starting at the rising edge of BITCLK.
TXDAI data is shifted out at the same rising edge of BITCLK. Data transmitted from RXDAI of
the internal application is sampled at the falling edge of BITCLK.
BITCLK
FS
TXDAI
RXDAI
AC75_HD_V00.202
MSB 14 13 12
MSB 14 13 12

Figure 29: Short Frame PCM timing

MSB 14 13 12
MSB 14 13 12

Figure 30: Long Frame PCM timing

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125 µs
2 1 LSB
LSB
2 1
125 µs
2 1 LSB
LSB
2 1
s
MSB
MSB
MSB
MSB
27.04.2006